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Pandemics: Then v. Now

Introduction

There is a reason pandemics are considered a factor of mass extinctions as they can kill off species at alarming rates. One of the most notable pandemics in human history is the Black Death in 14th century Europe. Although the plague did not result in a global human extinction, it did threaten human populations of Europe. The disease can be cured with modern antibiotics, but with the rise of deadly bacteria becoming resistant to treatment, our society could be as helpless as we once were 500 years ago. With the ease of global transmission due to modern day practices of the Anthropocene and rapid global climate changes, we face the possibility of a pandemic causing a mass extinction.

The Black Death

In October of 1347, The Black Death first arrived in Europe via trade ships returning from Asia. To the horror of those greeting the returned, almost everyone on the ship was dead or quite close to it (History.com Staff). The cause? Infected rats that acted as stowaways on the ship. The rats served as vectors which were immune to the Yesinia Pestis (the bacteria), but still had the ability to transfer the bacteria to different organisms. Flees on the ship bit the rats, and ingested the bacteria which in turn caused them to lose their ability to swallow. Once an inflicted flee bit a human, they threw up the contaminated rats blood, which therefore infected the human with the plague (History.com Staff). Once a human became infected, their future was not bright; their lymph nodes swelled and suffered through intense flu like symptoms, and in a matter of days, the illness usually resulted in death. The disease is highly contagious, and the animal vectors furthered the spread throughout Europe via trade ships. Poor sanitary conditions and overpopulation in cities contributed to the spread of the disease. In just 5 years, over 20 million people died which amounted to a drop in almost 2/3rds of the European population (History.com Staff).

The Great (antibiotic) Acceleration

Luckily today, modern antibiotics can cure a person of the plague. Antibiotics have not only beat the Black Plague, but have also cured hundreds of other bacterial infections. Although antibiotics are extremely beneficial, there has been a widespread miss-use of this treatment. Whether it be from doctors prescribing antibiotics before test results are revealed for the cause of illness, or people using antibiotics from a previous prescription incorrectly, antibiotics are being highly misused (CDC). Humans are not the only ones incorrectly consuming antibiotics. Livestock for food production are commonly given antibiotics to prevent infection from crowded living environments and incorrect diets.

Today just about 80 percent of antibiotic use is for livestock. (Helena Bottemiller). With the utter misuse of antibiotics, bacteria are mutating to become highly resistant to antibiotic treatment. Antibiotics destroy bacteria, but there can often be some bacteria that are naturally resistant to treatment due to mutations. When antibiotics kill majority of the bacteria, they are inherently reducing competition for the resistant bacteria, allowing them to multiply and grow. Resistant bacteria can then copy and transfer its DNA that codes for resistance to other bacteria via coagulation. Today, antibiotic resistant bacteria are a growing threat, as diseases are mutating to resist treatment. This is entirely a result of the human misuse of antibiotics. Diseases like Tuberculosis, MRSA, Gonorrhea, Salmonella and many more have developed strains that are resistant to antibiotics. Some of these superbugs are highly deadly as of last year over 700,000 people died from antibiotic resistant bacteria (Maryn Mckenna). The number of diseases gaining resistance to bacteria is growing each year, as are the number of cases.

The plague still exists today in over 10 countries throughout the world. Most deaths have occurred in Africa, as in certain regions there is not proper access to health care. Recently a segment of DNA that helps bacteria become resistant in meat has also been located in Yersinia Pestis. (Public Library of Science) Although researchers only recorded one case in Madagascar as being resistant to antibiotics, this finding indicates the definite possibility of the bacteria in meats to easily copy and transfer its DNA to the Yersinia Pestis. We could potentially have another global outbreak of the plague-and this time we would have no means of stopping it.

Anthropogenic Effects on Pandemics

In the 14th century the plague was confined to mostly Europe, with some deaths also occurring in Asia. Today, if there was a substantial outbreak of the plague or something similar, the current practices of the Anthropocene would could in a global pandemic. For the purpose of this topic, I am marking the start of the Anthropocene with the rise of the Great Acceleration in the 1950’s, when human activity surged exponentially and earth’s systems went through drastic transformations. Practices such as global transportation, tourism, urbanization and habits that lead to an increase of Co2 levels, create suitable conditions for a global spread of disease.

The first two prevalent anthropological human practices to discuss related to pathogen spread are global air transport and tourism. Both freight transport and human transport via air travel have increased dramatically in the last 50 years. In 2012 the number of people riding airplanes has increased 10 fold since 1950, from 31 million to 3,000 million (Supriya Kumar). The average flight length doubled since 1950, representing the increase in international flights. Freight transport has increased as well, with a 71% increase from 2001 to 2007(Supriya Kumar). All of this is to say the increase in flight travel makes it much simpler for a pathogen or vector to travel from one continent to the next, as they can do so in a matter of hours. Thousands of international flights take off daily, making the international spread of an outbreak highly likely given the amount of air traffic each day.

Similar trends are found in international tourism. Through the graph on the side, it is revealed that international tourism didn’t truly start until The Great Acceleration. Since then there has been an explosive increase in tourism, from less than a million arrivals in 1950 to just under 1,000 in2010. Tourists tend to meddle in natural habitats as such with the bat example in Kolbert. International tourists bring microbes that humans and animals alike may not have immunity to in that given region. Tourists can easily bring new bacteria or viruses to a country where the organisms are not immune to them, which could play a role in a mass extinction.

Urbanization is one of the most significant changes since the start of the Anthropocene. Urban populations have soared since the start of the Anthropocene, with less than a billion people in 1950, to around 3.5 billion in 2010. “In About 2008 humanity passed a historic milestone: over 50% of the global population now live in urban areas” (Will Steffen et al). Although people have have better access to health care by living in urban areas, antibiotic resistant diseases would have the ability to jump from person to person extremely easily, due to dense populations in urban areas. Public transportation, crowded streets, night clubs, schools etc. are all examples of people that interact in close proximity enough to rapidly spread an outbreak.

Human activities, as we have extensively discussed in class, have drastically raised green house gas emissions in the atmosphere. The increase of these gasses have caused a global temperature increase. The warmer climate brings along a host of consequences, one of them being mosquitos are moving north as a result of the temperature increase. (James Holland) With them many mosquitos are brining a multitude of blood born diseases including Dengue fever, Malaria, and Zika. These diseases are spreading to northern climates and inflicting people throughout the southern US. For Malaria, the developmental time for Plasmodium, or the Malaria parasite shortens with warmer weather. (James Holland) This makes it easier for mosquitos to transfer the disease to other organisms or people in higher latitudes.

Conclusion

Given the rise of antibiotic resistant bacteria and the increase in globalization, a global pandemic causing a mass extinction in multiple species is not a far fetched idea. If a mass extinction were to happen, temperatures could very likely drop due to the increase in vegetation after we have left. One bacteria could potentially cause another ice age. Although our healthcare has greatly improved in the last century, there are some diseases scientists would not be able to stop in time if there were to be a large outbreak. However, we can take preventative measures by being responsible antibiotic users, reducing green house gas emissions, and even washing our hands multiple times a day.